c.1300, "hard to manage, reckless, violent," from Old French estourdi "violent," originally "dazed," past participle of estourdir "to daze," from Vulgar Latin *exturdire, which is presumed to be from Latin intensive prefix ex + turdus "thrush." Perhaps the notion is of thrushes eating leftover grapes at wineries and acting drunk (Italian tordo "thrush" also means "simpleton," and French has the expression soûl comme une grive "drunk as a thrush"). OED, however, regards all this as "open to grave objection." Sense of "solidly built, strong and hardy" first recorded late 14c.